The ter mutation responsible for germ cell deficiency but not testicular nor ovarian teratocarcinogenesis in ter / ter congenic mice

The ter (teratoma) gene causes germ cell deficiency and a high incidence of congenital testicular teratomas derived from primordial germ cells in 129/Sv- ter strain mice. Ovarian teratomas in LTXBJ mice originate from ovarian parthenotes. In order to study the function of the ter gene in germ cell development and teratocarcinogenesis, we examined the influence of a foreign genetic background on the ter action by introducing the ter gene of 129/Sv- ter strain mice into C57BL/6J, LTXBJ and C3H/HeJ genetic backgrounds by the backcross method and by thus establishing B6- ter , LTXBJ- ter and C3H- ter ter congenic strains, respectively. Histological analysis showed that germ cell deficiency occurred in both sexes of the ter mutants, through the fetal stages to adulthood, but that congenital testicular teratocarcinogenesis did not occur after the fifth backcross generation. The ter/ter gonads were smaller than normal (+/+ or +/ ter ). Experimental testicular teratomas never developed from intratesticular grafts of B6- ter genital ridges. LTXBJ- ter/ter females had no ovarian teratomas. It is concluded that the ter gene is solely responsible for germ cell deficiency, but not testicular teratocarcinogenesis, in ter congenic strains having background genes other than 129/Sv- ter and that the ter gene is not involved in ovarian teratocarcinogenesis.